Firing mechanism for automatic firearms



June 16, 1936.

H. LAUF FIRING MECHANISM FOR AUTOMATIC FIREARMS Filed Nov. 21, 1954Patented June 16 1936 UNITED STATES FIRING MECHANISM FOR AUTOMATICFIREARMS Hans Lauf, Stockholm, Sweden Application November 21, 1934,Serial No. 754,101 In Sweden November 22, 1933 3 Claims.

The present invention relates to a firing mechanism intended forautomatic firearms, by means of which it is possible without specialreversing operation to fire at will single shots or a series of shots.

According to the invention the trigger is formed as a two-armed rockinglever, which when pulled by one lever arm acts for the discharging ofsingle shots and when pulled by the other lever arm acts for thedischarging of shots in series. This embodiment admits of a simplesolution of the problem of passing from one kind of firing to anotherwithout setting or reversing any special reversing members.

The invention is illustrated on the accompanying drawing, which shows avertical section through the trigger mechanism and adjacent parts of agas driven automatic firearm, the breech block of which is denoted byreference I and the breech body by reference 2.

The trigger it! is provided with two arms 20 and 2| and adapted to turnabout either one of the two spindles 22 and 23 according to whether itsupper arm 20 or its lower arm 2| is pulled, the oblong slots 24 and 24aextending below the spindles 22 and 23 respectively admitting of freemovement. In its position at rest the trigger I8 is suspended on bothspindles 22 and 23 when a projection on the trigger engages immediatelybelow the shoulder 26 of the trigger bar or sear 25. This trigger bar orsear is adapted to turn about the fulcrum pin 21 which is mounted in vthe pistol grip 36 secured beneath the breech body 2. If the lower arm2| is pulled back, the trigger 18 turns about its front spindle 22 andlifts the trigger bar or sear 25 so that its rear end 29 swingsdownwardly and becomes disengaged from the front surface of the lockingprojection 3 of the breech block. The latter is then thrown forward bythe closing spring II. The trigger l8 and the front end of the triggerbar or sear 25 remain in engagement, and the rear trigger bar end 29 iskept out of the way of the reciprocating breech block I, as long as thetrigger I8 is actuated. Thus the gun is being discharged in series.

If, however, the upper trigger arm 20 is pulled back the trigger I8turns about the rear spindle 23. The pawl 32, which is mounted on a pin30 secured in the trigger and adapted to turn about the pivot pin 33 inthe recess 3i of the trigger 18, then lifts the bevelled front end I! ofthe trigger bar or sear 25, which extends into the said recess. When therear portion 29 of the trigger bar or sear has liberated the breechblock I, so that the latter is thrown forward by spring II, the shoulder33 of the pawl 32 strikes against the lower surface of the front spindle22 and swings the upper end of the pawl forward, so that it glides offthe end I! of the trigger bar or sear 25 so that the latter may againget in the way of the breech block, which has been thrown forward, thusfiring a single shot.

A leaf spring 34 is secured in the pistol grip 36 by means of the pin 35and serves as pawl and sear actuating spring. The rear end of saidspring hooks over a toe on the trigger bar or sear 25 and permanentlytends to draw said toe downwards and swing end 29 of the sear upwards.The free end of the said spring 34 engages a rear projection of the pawl32, so that it always tends to move the upper end of the pawl rearward,consequently into a position below the front end I! of the trigger bar25. The point of contact of the pawl is chosen in such a manner that bymeans of the pin 30 of the trigger IS the pawl always is again returnedto its neutral position by spring 34.

Having now described my invention, what I claim as new and desire tosecure by Letters Patent is:

1. A double acting self-adjusting trigger mech anism for automaticfirearms for discharging single shots and shots in series respectively,in combination with a breech body having a breech block reciprocaltherein; said mechanism comprising a trigger having two arms, twospindles secured in the breech body acting as pivots respectively forsaid trigger arms, one spindle located behind the other in such a mannerthat when the upper arm is pulled the trigger turns about the rearspindle for single firing and when the lower arm is pulled the triggerturns about the front spindle for series firing, a double ended searmounted for oscillation in said breech body, one of the sear ends beingadapted for engaging said breech block to retain it in retractedposition, a flat spring tending to swing the sear into such engagement,means mounted on the trigger actuated by said spring for engagement withthe other of said sear ends, and said means tending to release suchengagement with the other sear end when encountering said front spindlewhile the trigger is being pulled.

2. A trigger mechanism according to claim 1, in which said meanscomprises a pawl normally engaging said front end of the sear, a rearlug on the pawl engaging said spring and a front lug on the pawlnormally free but adapted to contact with said front spindle to releasesaid sear when the trigger is actuated through said upper trigger arm.

3. A trigger mechanism according to claim 1, in which said meanscomprises a pawl normally engaging said front end of the sear, a rearlug on the pawl engaging said spring and a front lug on the pawlnormally free but adapted to contact with said front spindle to releasesaid 10 sear when the trigger is actuated through said upper triggerarm, said spring being secured substantially at its middle portion insaid breech body, a forward leg engaging said rear lug on the pawl inorder to normally engage the pawl with the front end of the sear, and arear extension of said spring engaging a toe formed on the searforwardly of the fulcrum point so as to raise the rear end of the searinto engagement with the breech block.

' HANS LAUF.

